﻿#include "SDL.h"
#include "SDL_image.h"
#include <iostream>
#include <string>
#undef main

//窗口属性
const int SCREEN_WIDTH = 640;
const int SCREEN_HEIGHT = 480;


SDL_Texture *load_image(SDL_Renderer *renderer, const std::string filename)
{
    SDL_Surface* loadedImage = nullptr;
    SDL_Texture *texture = nullptr;

    loadedImage = IMG_Load(filename.c_str());
    if(loadedImage != nullptr)
    {
        texture = SDL_CreateTextureFromSurface(renderer,loadedImage);
        SDL_FreeSurface(loadedImage);
    }
    else
    {
        std::cout << SDL_GetError() << std::endl;
    }
    return texture;
}

void ApplySurface(int x, int y, SDL_Texture *texture, SDL_Renderer *render)
{
    SDL_Rect pos;
    pos.x = x;
    pos.y = y;
    SDL_QueryTexture(texture, nullptr, nullptr, &pos.w, &pos.h);

    SDL_RenderCopy(render, texture, nullptr, &pos);
}

int main()
{
    //表面
    SDL_Texture *image = nullptr;
    SDL_Window *screen = nullptr;
    SDL_Renderer *renderer = nullptr;
    SDL_Surface* gScreenSurface =nullptr;
    SDL_Texture *background = nullptr;
    bool quit = false;

    if (SDL_Init(SDL_INIT_EVERYTHING) == -1)
    {
        std::cout << SDL_GetError() << std::endl;
    }

    screen = SDL_CreateWindow("Event Driven",
                              SDL_WINDOWPOS_CENTERED,
                              SDL_WINDOWPOS_CENTERED,
                              SCREEN_WIDTH,
                              SCREEN_HEIGHT,
                              SDL_WINDOW_SHOWN);
    if(screen == nullptr)
    {
          std::cout << SDL_GetError() << std::endl;
    }

    //修改屏幕的背景颜色
    gScreenSurface=SDL_GetWindowSurface(screen);
    /* Fill screen with some color */
    SDL_FillRect(gScreenSurface, nullptr, 0xCC9966);

    renderer = SDL_CreateRenderer(screen, -1, SDL_RENDERER_ACCELERATED|SDL_RENDERER_PRESENTVSYNC);
    if(renderer == nullptr)
    {
        std::cout << SDL_GetError() << std::endl;
        return 1;
    }

    background = SDL_CreateTextureFromSurface(renderer,gScreenSurface); //从surface 转换到 texture
    ApplySurface(0,0,background,renderer);                              //利用渲染器将颜色绘制到窗口中

    image = load_image(renderer,"E://workspace//FFMEPG//SDL//sources//background.png");
    if(image == nullptr)
    {
        std::cout << SDL_GetError() << std::endl;
        return 1;
    }

    int iW=0, iH=0;
    SDL_QueryTexture(image, nullptr, nullptr, &iW, &iH);
    int x = SCREEN_WIDTH / 2 - iW / 2;
    int y = SCREEN_HEIGHT / 2 - iH / 2;
    ApplySurface(x, y, image, renderer);

    SDL_RenderPresent(renderer);

    SDL_Event event;
    while (quit == false) //当用户不想退出时
    {
        //函数SDL_PollEvent() 的作用是从事件队列底部取出一个事件并将其事件数据粘贴到一个SDL_Event类型的结构体中
        while (SDL_PollEvent(&event))
        {
            //若用户点击量窗口右上角的关闭按钮
            if(event.type == SDL_QUIT)
            {
                //退出程序
                quit = true;
            }

            //键盘按键按下处理
            if(event.type == SDL_KEYDOWN)
            {
                switch (event.key.keysym.sym) {
                case SDLK_a:
                    quit = true;
                    break;
                case SDLK_b:
                    std::cout << "keyboard b clicked" << std::endl;
                    break;
                default:
                    break;
                }
            }

            //鼠标三键按下处理
            if(event.type == SDL_MOUSEBUTTONDOWN)
            {
                if(SDL_BUTTON_LEFT == event.button.button)
                {
                    std::cout << " ========================== " << std::endl;
                    int px = event.button.x;
                    int py = event.button.y;
                    std::cout << " Left X position: " << px << std::endl;
                    std::cout << " Left Y position: " << py << std::endl << std::endl;
                }
                else if(SDL_BUTTON_RIGHT == event.button.button)
                {
                    std::cout << " ========================== " << std::endl;
                    int px = event.button.x;
                    int py = event.button.y;
                    std::cout << " Right X position: " << px << std::endl;
                    std::cout << " Right Y position: " << py << std::endl << std::endl;
                }
                else if(SDL_BUTTON_MIDDLE == event.button.button)
                {
                    std::cout << " ========================== " << std::endl;
                    int px = event.button.x;
                    int py = event.button.y;
                    std::cout << " Middle X position: " << px << std::endl;
                    std::cout << " Middle Y position: " << py << std::endl << std::endl;
                }
            }
        }
    }

    SDL_DestroyTexture(image);
    SDL_DestroyRenderer(renderer);
    SDL_FreeSurface(gScreenSurface);
    SDL_DestroyWindow(screen);
    SDL_Quit();
    return 0;
}
